Process for making alkaline earth metal borated sulfonates

ABSTRACT

An improved process for preparing an alkaline earth metal borated sulfonate comprising reacting a mixture of the following materials(A) (1) at least one of an oil soluble sulfonic acid or alkaline earth sulfonate salt or mixtures thereof (2) at least one source of an alkaline earth metal; and (3) at least one source of boron, in the presence of a mixture of comprising (4) at least one hydrocarbon solvent; and (5) at least one low molecular weight alcohol; and (6) from 0 to less than 10 mole percent, relative to the source of boron, of an overbasing acid, other than the source of boron; and (B) heating the reaction product of (A) to a temperature above the distillation temperatures of (4) and (5) to distill (4), (5) and water of reaction, wherein no additional water is added in the process.

FIELD OF THE INVENTION

The present invention is directed to an improved process for makingalkaline earth metal borated sulfonates.

BACKGROUND OF THE INVENTION

Preventing and/or reducing wear, as well as improving frictionproperties, are very important properties of lubricating oilcompositions. Boron-containing additives, especially alkaline earthmetal borated sulfonates, have been found not only to have excellentanti-friction properties when employed in lubricating oil compositionsbut also to provide detergent, anti-rust, anti-corrosion, and extremepressure properties.

The present invention is directed to the discovery of an improved methodof making alkaline earth metal borated sulfonates.

BACKGROUND ART

Inoue et al., U.S. Pat. No. 4,683,126, discloses a method for producingan alkaline earth metal borate dispersion comprising two steps. Thefirst step comprises reacting at 20°-100° C. a mixture of the followingingredients (A) to (E): (A) 100 parts by weight of the oil-solubleneutral sulfonate of an alkaline earth metal, (B) 10-100 parts by weightof the hydroxide or oxide of an alkaline earth metal, (C) boric acid inan amount which is 0.5-6.5 times in mol that of the ingredient (B), (D)5-50 parts by weight of water, and (E) 50-200 parts by weight of adilution solvent. The second step comprises heating the resultingreaction mixture of the first step to 100°-200° C. to remove the waterand a part of the dilution solvent as required.

Hellmuth et al., U.S. Pat. No. 3,480,548 discloses a lubricating oilcomposition prepared by reacting a lubricating oil dispersion of analkaline earth metal carbonate and alkaline earth metal hydrocarbonsulfonate with a boron compound selected from the group consisting ofboric acids, boron oxides, and aqueous alkyl esters of boric acids.

Hellmuth et al., U.S. Pat. No. 3,679,584 discloses a process forincreasing the alkaline earth metal ratio of an alkaline earth metalcarbonate overbased alkaline earth metal sulfonate lubricating oilcomposition comprising introduction into a lubricating oil mediumcontaining a colloidal-like dispersion of an alkaline earth metalcarbonate overbased alkaline earth metal sulfonate, an alkaline earthmetal hydroxide and boric acid and subsequently contacting the resultantmixture with carbon dioxide.

Fischer et al., U.S. Pat. No. 4,744,920 discloses a carbonated overbasedproduct that has been borated. Specifically, the process comprises (a)mixing an overbased sulfonate and any required inert liquid medium, (b)borating the mixture (a) with a borating agent at a temperature lessthan at which substantial foaming occurs, (c) raising the temperature ofthe mixture (b) to that temperature in excess of the boiling point ofwater within the mixture (b), (d) separating substantially all of thewater from the reaction mixture (c) while retaining substantially all ofthe carbonate in the mixture (c) and, (e) recovering the product (d) ashigh carbonate content borated product.

Schlicht, U.S. Pat. No. 4,965,003 discloses a process for preparing aborated, overbased oil-soluble metal detergent additive for lubricants,said process comprising (a) mixing a metal salt dissolved in ahydrocarbon solvent with a metal base and a polar solvent; (b) treatingsaid metal salt mixture at a temperature ranging from about 10° C. toabout 100° C. while passing an acid gas through the mixture; (c)filtering said treated mixture at a temperature of about 10° C. to about100° C.; (d) adding a borating agent to said filtrate and reacting saidfiltrate for a period of about 0.25 to about 5.0 hours at a temperatureranging from about 15° C. to about 100° C.; (e) heating said boratedmixture at a temperature sufficiently high to distill a major portion ofthe polar solvent and water therefrom; (f) cooling the distilled boratedmixture to below the boiling point of the remaining solvent andfiltering said cooled filtrate mixture; and (g) stripping the cooleddistilled filtrate mixture under a pressure ranging from about 10 toabout 200 mm Hg at a temperature ranging from about 20° C. to about 150°C., thereby recovering the borated metal detergent additive.

Schlicht et al., U.S. Pat. No. 4,965,004 discloses (a) adding a boratingagent to an overbased metal salt in the presence of a protic solvent anda hydrocarbon solvent and reacting for a period of about 0.25 to about5.0 hours at a temperature ranging from about 15° C. to about 100° C.;(b) heating said borated metal salt mixture at a temperaturesufficiently high to distill an amount of distillate equal to at leastabout 80 percent of the protic solvent fed; (c) cooling the distilledborated mixture to below the boiling point of the remaining solvent andfiltering said cooled filtrate mixture; and (d) stripping the cooleddistilled filtrate mixture under a pressure ranging from about 10 toabout 200 mm Hg at a temperature ranging from about 20° C. to about 150°C., and recovering the borated metal detergent additive.

SUMMARY OF THE INVENTION

Accordingly, in its broadest embodiment, the present invention isdirected to a process for preparing an alkaline earth metal boratedsulfonate comprising:

-   -   (a) reacting        -   (i) at least one of an oil soluble suifonic acid, an            alkaline earth sulfonate salt, or a mixtures thereof;        -   (ii) at least one source of alkaline earth metal;        -   (iii) at least one source of boron, in the presence of a            mixture comprising:            -   (1) at least one hydrocarbon solvent;            -   (2) at least one low molecular weight alcohol; and        -   (iv) from 0 to less than 10 mole percent, relative to the            source of boron, of an overbasing acid, other than the            source of boron; and    -   (b) heating the reaction product of (a) to a temperature above        the distillation temperatures of the hydrocarbon solvent and the        low molecular weight alcohol to distill the hydrocarbon solvent        the alcohol and the water generated from the reaction, wherein        no additional water is added in the process.

DETAILED DESCRIPTION OF THE INVENTION

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example and are herein described in detail. It should be understood,however, that the description herein of specific embodiments is notintended to limit the invention to the particular forms disclosed, buton the contrary, the intention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims.

The term “Total Base Number” or “TBN” refers to the amount of baseequivalent to milligrams of KOH in 1 gram of sample. Thus, higher TBNnumbers reflect more alkaline products and therefore a greateralkalinity reserve. For the purposes of this invention, TBN isdetermined by ASTM Test No. D2896.

Each and every numerical range and/or value, regardless whether itappears immediately or closely following the term “about” should beunderstood to encompass those variations that may represent the range ofexperimental error that occurs in any measurement.

It has been discovered that the borated sulfonate made by the processdisclosed within results in low sediment.

Process for Preparing an Alkaline Earth Metal Borated Sulfonate

The present invention involves an improved process for preparing analkaline earth metal borated sulfonate.

The process for preparing an alkaline earth metal borated sulfonatecomprises:

-   -   (a) reacting        -   (i) at least one of an oil soluble sulfonic acid, an            alkaline earth sulfonate salt, or a mixtures thereof;        -   (ii) at least one source of an alkaline earth metal;        -   (iii) at least one source of boron, in the presence of a            mixture comprising:            -   (1) at least one hydrocarbon solvent;            -   (2) at least one low molecular weight alcohol; and        -   (iv) from 0 to less than 10 mole percent, relative to the            source of boron, of an overbasing acid, other than the            source of boron; and    -   (b) heating the reaction product of (a) to a temperature above        the distillation temperatures of the hydrocarbon solvent and the        low molecular weight alcohol to distill the hydrocarbon solvent,        the alcohol and the water generated from the reaction, wherein        no additional water is added in the process.        Hydrocarbon Solvent

The hydrocarbon solvent which may be used in the present process may beselected from the group consisting of n-pentane, n-hexane, cyclohexane,n-heptane, n-octane, isooctane, n-decane, benzene, toluene, xylene andmixtures thereof. Preferably, the hydrocarbon solvent is an aromaticsolvent and is selected from the group of solvents consisting of xylene,benzene and toluene. The most preferred aromatic solvent is xylene.

Low Molecular Weight Alcohol

The low molecular weight alcohol must have a boiling point sufficientlylow so that it may be easily distilled off after the reaction hasoccurred. Typically, the low molecular weight alcohol will have fromabout 1 to about 13 carbon atoms and a molecular weight no higher thanabout 200. In one embodiment, the low molecular weight alcohol is a lowmolecular weight monohydric alcohol. In a more preferred embodiment thelow molecular weight monohydric alcohol which may be used in the presentprocess may be selected from the group consisting of (C1-C13) alcoholsand glycol monoethers and monoesters. Preferably, the low molecularweight alcohol is a monohydric alcohol selected from the groupconsisting of methanol, ethanol, propanol, isooctanol, cyclohexanol,cyclopentanol, isobutyl alcohol, benzyl alcohol, beta-phenyl-ethylalcohol, 2-ethylhexanol, dodecanol, tridecanol, 2-methylcyclohexanol,monomethyl ether of ethylene glycol, monobutyl ether of ethylene glycol,sec-pentyl alcohol, and tert-butyl alcohol. The most preferred lowmolecular weight monohydric alcohol is methanol.

In a further embodiment, the low molecular weight alcohol is apolyhydric alcohol; in a preferred embodiment, the polyhydric alcohol isa dihydric alcohol, such as ethylene glycol.

Oil Soluble Sulfonic Acid or Alkaline Earth Metal Sulfonate Salt

In the present invention, either an oil soluble sulfonic acid or an oilsoluble alkaline earth metal sulfonate salt is used in the process forpreparing a borated sulfonate.

Sulfonic Acid

In one embodiment of the present invention, an oil soluble sulfonic acidmay be used in the process for preparing a borated sulfonate. Thesulfonic acid may be derived from sulfonating alkyl aromatics,especially alkylbenzene and alkyltoluene, such as linear alkylbenzene oralkyltoluene, branched alkylbenzene or alkyltoluene, or benzene ortoluene having a polyalkenyl group (e.g., polyisobutene) with sulfuricacid, sulfur trioxide, chlorosulfonic acid or sulfamic acid. Sulfonicacid preparation is well known in the art.

In another embodiment of the present invention, the oil soluble sulfonicacid may be a polyalkylene sulfonic acid, especially a polyisobutenesulfonic acid. Sulfonic acids prepared from polyisobutenes are thesubject of U.S. Pat. No. 6,410,491 which is incorporated herein byreference in its entirety and the sulfonate that is prepared from thesulfonic acid derived from polyisobutene is disclosed in U.S. Pat. No.6,632,781 which is incorporated herein by reference.

Preferably, the sulfonic acid is obtained by the sulfonation of amixture of primarily mono alkylbenzenes which are obtained from thealkylation of benzene by a mixture of heavy alpha linear olefins havingfrom about 20 to about 24 carbon atoms.

In another embodiment the sulfonic acid is obtained by the sulfonationof a mixture of primarily mono alkyltoluene which are obtained from thealkylation of toluene by a mixture of heavy alpha linear olefins havingfrom about 20 to about 24 carbon atoms.

Alkylbenzene may be derived from the alkylation of an aromatic compoundwherein the alkylation is the reaction of a linear olefin whichcomprises at least 16 carbon atoms and an aromatic compound in thepresence of a Lewis Acid. Preferably, the olefin is a normal alphaolefin that has from about 18 carbon atoms to about 26 carbon atoms.Alkylated aromatics, the process of which is well known in the art, maybe derived from numerous processes including, but not limited to, theprocesses disclosed in US Patent Application Publication Nos. US2005/0202954, US 2005/0203323, and US 2005/0203322.

Alkaline Earth Metal Sulfonate Salt

In another embodiment of the present invention, an alkaline earth metalsulfonate salt may be used in the process to prepare a boratedsulfonate. The alkaline earth metal sulfonate salt may be derived fromreacting a source of an alkaline earth metal with an alkylbenzenesulfonic acid. Preferably, when employing a linear alkylbenzene, thesynthetic linear alkylbenzene sulfonic acid produced, therefrom, may beneutralized with a source of an alkaline earth metal. In a morepreferred embodiment, the linear alkylbenzene sulfonic acid isneutralized with an alkaline earth metal hydroxide, such as, but notlimited to, calcium hydroxide or magnesium hydroxide.

An important feature of this invention is that the alkaline earth metalsulfonate salt, if used, contains an amount of overbasing acid otherthan the source of boron, such that the product borated sulfonatecontains from 0 to less than 10 mole percent, relative to the source ofboron, of an overbasing acid, other than the source of boron. In apreferred embodiment the alkaline earth metal sulfonate salt does notcontain an overbasing acid other than the source of boron. Preferablythe alkaline earth metal sulfonate salt is a neutral alkaline earthmetal sulfonate salt. Preferably the alkaline earth metal sulfonate salthas a TBN of from about 0 to about 50.

The sulfonate salts are those having a substantially oleophiliccharacter and which are formed from organic materials. Organicsulfonates are well known materials in the lubricant and detergent arts.The sulfonate compound should contain on average from about 10 to about40 carbon atoms, preferably from about 12 to about 36 carbon atoms andpreferably from about 14 to about 32 carbon atoms.

Typically, the sulfonate is an alkyl aromatic sulfonate wherein thealkyl group is preferably derived from a normal alpha olefin. Morepreferred, the aromatic moiety is benzene or toluene and the alkyl grouphas from about 20 to about 24 carbon atoms. The most preferred sulfonatecomposition is a monosulfonated alkylated benzene.

Alkaline Earth Metal

A source of an alkaline earth metal is also reacted with theaforementioned compounds (i.e., at least one oil soluble sulfonic acidor alkaline earth metal sulfonate salt or mixtures thereof) in thepresence of a mixture comprising a hydrocarbon solvent and a lowmolecular weight alcohol. Preferably, the alkaline earth metal used inthe reaction of the present invention is an alkaline earth metalhydroxide or oxide. The most preferred source of alkaline earth metal iscalcium hydroxide (lime).

Source of Boron

A source of boron is also reacted with the aforementioned compounds(i.e., at least one oil soluble sulfonic acid or alkaline earth metalsulfonate salt or mixtures thereof, and source of an alkaline earthmetal) in the presence of a mixture comprising a hydrocarbon solvent anda low molecular weight alcohol. Boron sources include polymers of boricacid, boron anhydride, boron esters, and similar materials. The mostpreferred source of boron is orthoboric acid.

Overbasing Acid

The term “overbasing acid,” as used herein, refers to an acid capable ofproviding an oil-soluble metal sulfonate with greater than astoichiometric amount of metal to sulfonic acid. The most commonoverbasing acid is carbon dioxide; other overbasing acids include sulfurdioxide and sulfur trioxide. The acid itself may be part of theoverbasing process, or alternatively a source of an overbasing acid suchas ethylene carbonate may be used to introduce the overbasing acid.

Process and Diluent Oils

If the borated sulfonate is viscous, an inert liquid medium may beemployed to reduce the viscosity. The inert liquid medium can also serveto disperse the product and to facilitate mixing of the ingredients. Apreferred inert liquid medium is lubricating oil. As disclosed in Fuelsand Lubricants Handbook, edited by George E. Totten, p. 199 (2003), alubricating oil or “base fluid can be of mineral origin, syntheticchemical origin or biological origin. While mineral oil basestocks [arederived] from petroleum fractionation, synthetic basestocks aremanufactured through transformations of petroleum-derived organicchemicals. Partly synthetic (semisynthetic) basestocks are compatiblemixtures of mineral oil and synthetic basestocks.” Basestocks ofbiological origin are derived from vegetable and animal oils.

The inert liquid medium may be omitted where, for example, the productis extruded. In such cases mechanical mixing replaces the need for asolvent.

Foam inhibitors and other processing aids may also be added.

Process—Neutralization of Sulfonic Acid

In a typical process of the present invention, hydrocarbon solvent isfirst premixed with a low molecular weight alcohol and a source of analkaline earth metal. Generally this premixing is done near ambienttemperatures, i.e. at about 15-40° C. Sulfonic acid is next added withagitation. Typically, sulfonic acid is added over a period of timewherein the temperature ranges from about 20° C. to about 40° C. Due tothe heat of reaction, the temperature increases to from about 20° C. toabout 55° C. The mixture is held for approximately 5 to 20 minutes atfrom about 40° C. to about 50° C. to ensure that the sulfonic acid isadequately neutralized by the source of alkaline earth metals to make aneutral alkaline earth metal sulfonate. If the alkaline earth sulfonatesalt is used instead of the sulfonic acid this neutralization step isomitted.

The source of boron, such as boric acid, is added over a period of fromabout 5 minutes to about 20 minutes, while the temperature wasmaintained at from about 30° C. to about 50° C. The reaction is held atfrom about 30° C. to about 50° C. for from about 5 minutes to about 15minutes. The reaction mixture may be held at an intermediate temperatureof from about 70° C. to about 80° C. to reduce sediment in the finalproduct. Methanol, water and xylene are then eliminated throughseparation methods that are well known in the art, such as distillation.Typically, a distillation step is used in which the above reactionmixture is heated to from about 125° C. to about 140° C. Typically, adiluent oil, such as 100N oil, will be employed and will be added to themixture before all the hydrocarbon solvent is distilled. The un-reactedlime and boric acid are eliminated by conventional methods, such ascentrifugation or filtration. The final product will have a typical basenumber of from about 10 to about 250 mg KOH/g.

When employed, the overbasing acid other than the source of boron may beintroduced with the alkaline earth metal sulfonate salt, or introducedin situ during the reaction, or introduced after the reaction. In apreferred embodiment, the present process does not employ an overbasingacid other than the source of boron.

In a preferred embodiment of the present invention, the boratedsulfonate is a borated calcium sulfonate.

The borated sulfonate of this process contains from 0 to less than 10mole percent, relative to the source of boron, of an overbasing acid,other than the source of boron. In a preferred embodiment the processfor preparing the alkaline earth metal borate sulfonate contains nooverbasing acid, such as carbon dioxide, sulfur oxides etc., other thanthe source of boron. Additionally, although water may be a by-product ofthe reaction, no water is added to the reaction mixture.

In a preferred embodiment of the present invention the weight ratio oflow molecular weight alcohol to source of an alkaline earth metal is atleast 0.2, preferably at least 0.35, more preferably at least 0.5. Mostpreferably, the weight ratio of low molecular weight alcohol to sourceof an alkaline earth metal is at least 0.65.

The boron content of the sulfonates employed in the present invention isfrom about 3.0 wt % to about 5.0 wt %. More preferred the amount ofboron in the sulfonate is from about 3.5 wt % to about 4.5 wt %. Mostpreferred the amount of boron in the sulfonate is from about 3.7 wt % toabout 4.3 wt %.

The water content of the borated sulfonate is typically less than 1.0%by weight. If the separation does not occur during processing, thenduring storage, the boron content may be diminished by havingunacceptably high levels of water in the sulfonate product. Preferably,the water content of the sulfonate product is less than 1.0% by weightand more preferably less than 0.50% by weight.

The invention is further illustrated by the following examples, whichset forth particularly advantageous method embodiments. While theexamples are provided to illustrate the present invention, they are notintended to limit it.

EXAMPLES Example A Sulfonic Acid Preparation

In a typical preparation benzene is alkylated with a mixture of C20-C24heavy alpha linear olefins thereby producing a mixture ofmonoalkylbenzenes. Sulfur is burned to produce SO2 which is converted toSO3 using V2O5 catalyst in a fixed bed reactor.

Sulfonic acid is obtained by the sulfonation of a mixture ofmonoalkylbenzenes with SO3 at a charge mole ratio of SO3/alkylate of0.85 to 1.00. The alkylate at 55-60O C is contacted with a SO3/airmixture in a falling film sulfonator.

Example 1

To a 1 liter glass reactor, equipped with a heating mantle and mixer,was added 464 grams of mixed xylenes solvent. To the same reactor, 62grams of methanol was added, followed by 52 grams of lime (calciumhydroxide). To the above mixture, which was at ambient temperature, 150grams of sulfonic acid (as prepared in Example A) was added. Thetemperature increased to 30 degrees C. 74 grams boric acid was thenadded to the reactor. The temperature increased to 35 degrees C. Thereactor was then heated to 127 degrees C. over a period of 2 hours, toremove the water and methanol as well as some xylene. 80 grams Group Ibase oil was added to the reactor. The sediment in the reactor wasmeasured at 1.8 vol %. The reactor was then heated to 170 degrees C. and1 PSIA to distill the xylene. The resulting product had an amount ofsediment of 3.6 vol %.

The product was then filtered and had the following characteristics:

Calcium: 9.4 wt % Boron: 4.1 wt % BN: 173 Viscosity 390 cST at 100degrees C.

Example 2

To a 1 liter glass reactor, which is equipped with a heating mantle andmixer, was added 234 grams of mixed xylenes solvent. To the samereactor, 50 grams of lime (calcium hydroxide) was added. To the abovemixture, which was at ambient temperature, 150 grams of sulfonic acid(as prepared in Example A) was added. The temperature increased to 40degrees C. The reactor was cooled to 18 degrees C. and 974 grams ofboric acid was added. 62 grams of methanol was added to the reactor andthe temperature increased to 32 degrees C.

Over a 2 hour period, the reactor was heated to 127 degrees C. in orderto remove water, methanol and some xylene. 80 grams of Group I base oilwas added to the reactor and the amount of sediment was measured at 2.0vol %. the reactor was then heated to 170 degrees C. and 1 PSIA todistill the xylene. The resulting product had an amount of sediment of3.2 vol %.

Example 3

To a 1 liter glass reactor, which is equipped with a heating mantle andmixer, was added 406 grams of mixed xylenes solvent. To the samereactor, 50 grams of lime (calcium hydroxide) was added. To the abovemixture, which was at ambient temperature, 150 grams of sulfonic acid(as prepared in Example A) was added. The temperature increased to 44degrees C. The reactor was cooled to 18 degrees C. and 74 grams of boricacid was added. 62 grams of methanol was added to the reactor whichcaused the temperature to increase to 32 degrees C. Over a 2 hourperiod, the reactor was heated to 127 degrees C. in order to removewater, methanol and some xylene. 80 grams of Group I base oil was addedto the reactor and the amount of sediment was measured at 1.8 vol %. Thereactor was then heated to 170 degrees C. and 1 PSIA to distill thexylene.

The resulting product had an amount of sediment of 3.6 vol %.

Example 4

To a 1 liter glass reactor, which was equipped with a heating mantle andmixer, was added 300 grams of mixed xylenes solvent. To the samereactor, 50 grams of lime (calcium hydroxide) was added. To the abovemixture, which was at ambient temperature, 150 grams of sulfonic acid(as prepared in Example A) was added. The temperature increased to 44degrees C. The reactor was cooled to 18 degrees C. and 74 grams of boricacid was added. 42 grams of methanol was added to the reactor whichcaused the temperature to increase to 32 degrees C. Over a 2 hourperiod, the reactor was heated to 127 degrees C. in order to removewater, methanol and some xylene. 80 grams of Group I base oil was addedto the reactor and the amount of sediment was measured at 1.8 vol %. Thereactor was then heated to 170 degrees C. and 1 PSIA to distill thexylene.

The resulting product had an amount of sediment of 3.6 vol %.

Example 5

To a 1 liter glass reactor, which was equipped with a heating mantle andmixer, was added 300 grams of mixed xylenes solvent. To the samereactor, 47 grams of lime (calcium hydroxide) was added. To the abovemixture, which was at ambient temperature, 150 grams of sulfonic acid(as prepared in Example A) was added. The temperature increased to 43degrees C. The reactor was cooled to 18 degrees C. and 74 grams of boricacid was added. 30 grams of methanol was added to the reactor whichcaused the temperature to increase to 24 degrees C.

Over a 2 hour period, the reactor was heated to 127 degrees C. in orderto remove water, methanol and some xylene. 80 grams of Group I base oilwas added to the reactor and the amount of sediment was measured at 2.8vol %. The reactor was then heated to 170 degrees C. and 1 PSIA todistill the xylene.

The resulting product had an amount of sediment of 4.8 vol %.

Example 6

To a 1 liter glass reactor, which was equipped with a heating mantle andmixer, was added 300 grams of mixed xylenes solvent. To the samereactor, 50 grams of lime (calcium hydroxide) was added. To the abovemixture, which was at ambient temperature, 150 grams of sulfonic acid(as prepared in Example A) was added. The temperature increased to 43degrees C. The reactor was cooled to 18 degrees C. and 74 grams of boricacid was added. 20 grams of methanol was added to the reactor whichcaused the temperature to increase to 29 degrees C.

Over a 2 hour period, the reactor was heated to 127 degrees C. in orderto remove water, methanol and some xylene. 80 grams of Group I base oilwas added to the reactor and the amount of sediment was measured at 10.4vol %. The amount of sediment in the final product was too great toomeasure.

Comparative Example 1

This comparative Example was run according to the method of Inoue etal., U.S. Pat. No. 4,683,126. To a 1 liter glass reactor, which wasequipped with a heating mantle and mixer, was added 234 grams of mixedxylenes solvent. To the same reactor, 50 grams of lime (calciumhydroxide) was added. To the same reactor, 150 grams of sulfonic acid(as prepared in Example A) was added.

74 grams of boric acid was added at 18 degrees C. Next, 15 grams ofwater was added. The reactor was then heated to 60 degrees C. andanother 15 grams of water was added. The reactor was then held at 79degrees C. for one hour. The sediment was then measured at 40 vol %. Thereactor was heated to 127 degrees C. over a period of 100 minutes. Theamount of sediment at the end of the reaction was 48%. This amount ofsediment indicates that the lime was barely, if at all incorporated inthis reaction.

TABLE 1 Methanol/lime Sediment at Final sediment, Example wt-% ratio127° C. wt-% 1 1.24 1.8 3.6 2 1.24 2.0 3.2 3 1.24 0.8 3.6 4 0.83 1.8 3.65 0.62 2.8 4.8 6 0.41 10.4 — Comparative 0 40 48 Example 1

This comparison shows that the use of added water in the process to makea borated sulfonate leads to such an increase in sediment as to make theprocess untenable. In addition, there appears to be a threshold amountof low molecular weight alcohol that, when added to the reactionmixture, yields a final product that has a decreased amount of sediment.

It is understood that although modifications and variations of theinvention can be made without departing from the spirit and scopethereof, only such limitations should be imposed as are indicated in theappended claims.

1. A process for preparing an alkaline earth metal borated sulfonatecomprising: (a) reacting (i) at least one of an oil soluble sulfonicacid, an alkaline earth sulfonate salt, or a mixtures thereof; (ii) atleast one source of alkaline earth metal; (iii) at least one source ofboron, in the presence of a mixture comprising: (1) at least onehydrocarbon solvent; (2) at least one low molecular weight alcohol; and(iv) from 0 to less than 10 mole percent, relative to the source ofboron, of an overbasing acid, other than the source of boron; and (b)heating the reaction product of (a) to a temperature above thedistillation temperatures of the hydrocarbon solvent and the lowmolecular weight alcohol to distill the hydrocarbon solvent, the alcoholand the water generated front the reaction, wherein no additional wateris added in the process.
 2. The process according to claim 1, whereinthe oil soluble sulfonic acid is an aromatic sulfonic acid.
 3. Theprocess according to claim 2, wherein the aromatic sulfonic acid is alinear alkylbenzene sulfonic acid.
 4. The process according to claim 3,wherein the linear alkylbenzene sulfonic acid is derived from thesulfonation of alkylates, which are in turn derived from the alkylationof an aromatic material, wherein the alkyl group of the linearalkylbenzene sulfonic acid comprises at least 16 carbon atoms.
 5. Theprocess according to claim 1, wherein the low molecular weight alcoholis a monohydric alcohol.
 6. The process according to claim 5 wherein thelow molecular weight monohydric alcohol is methanol.
 7. The processaccording to claim 1, wherein the hydrocarbon solvent is xylene.
 8. Theprocess according to claim l, wherein the source of alkaline earth metalis calcium hydroxide.
 9. The process according to claim l, wherein thesource of boron is boric acid.
 10. The process according to claim 1,wherein the weight ratio of low molecular weight alcohol to source ofalkaline earth metal is at least 0.2:1.
 11. The process according toclaim 1, employing no overbasing acid other than the source of boron.12. The process according to claim 2, wherein the aromatic sulfonic acidis an alkyltoluene sulfonic acid.
 13. The process according to claim 12,wherein the alkyltoluene sulfonic acid is a linear alkyltoluene sulfonicacid.
 14. The process according to claim 12, wherein the alkyltoluenesulfonic acid is a branched alkyltoluene sulfonic acid.
 15. The processaccording to claim 2, wherein the aromatic sulfonic acid is apolyalkenyl toluene sulfonic acid.
 16. The process according to claim13, wherein the linear alkyl group of the linear alkyltoluene sulfonicacid comprises at least 16 carbon atoms.
 17. The process according toclaim 16, wherein the linear alkyl group of the linear alkyltoluenesulfonic acid comprises about 16 to about 28 carbon atoms.